partial void Deletebuilding(building instance);
 partial void Updatebuilding(building instance);
		private void detach_buildings(building entity)
		{
			this.SendPropertyChanging();
			entity.category = null;
		}
 partial void Insertbuilding(building instance);
		private void attach_buildings(building entity)
		{
			this.SendPropertyChanging();
			entity.category = this;
		}